Antenna system



April 24, 1951 H. c. A. VAN DUUREN ANTENNA SYSTEM Filed Dec. 21, 1940Patented Apr. 24, 1951 ANTENNA SYSTEM Hendrik C. A. van Duuren,Wassenaar, Netherlands Application December 21, 1940, Serial No. 371,176

In the Netherlands December 21, 1939 17 claims. 1

The present invention relates to a directional antenna, system forwireless reception comprising a plurality of rhombic antennae of similarform and similarly arranged, such as in horizontal end-to-end array.These antennae have lead-in connection from corresponding angular pointsof each rhomb, each constituting a lead-in point for the rhomb, and eachrhomb has maximum effectiveness of reception in a vertical plane whichextends symmetrically through the rhomb from the lead-in end to theopposite or terminating end. In this end-to-end array, the maximumeectiveness of reception lies in a direction which is the same for allrhombs, this direction extending at an angle to the horizontal and beinga function of the length of the wave received. A Well known system ofthis general type is known as the MUSA system (abbreviated from MultipleUnit Steerable Antenna) which is described in the Bell System TechnicalJournal of 1937, pages 337 et seq. This MUSA system utilizes a number ofrhombs arranged end-to-end in a row and connected to each other and tothe receiver by the Way of phase rotators or phase Shifters which permitof the modiiication, within certain limits, of this angle of directivityin the vertical plane from which the combination of rhombs receivessignals with maximum eiectiveness for a given wave length.

It is a requirement of this MUSA system, as will hereinafter appear,that each successive phase shifter shall shift the received currentthrough an angle which, With respect to that of the first phase shifter,is greater by a factor which is a whole number.l This necessitates anexpensive arrangement.

The directional characteristic of these multiple unit antennae systemshaving steerable directivity can be deduced or determined from onedirectional characteristic which depends only on the position of theindividual antenna relatively to each other and to their interconnection(hereinafter referred to as the group directional characteristic) andalso from the directional characteristic of a single rhomb (hereinafterreferred to as the individual directional characteristic). The relativetransmitting or receiving intensity in a certain direction isproportional to the product of the intensities of the above twodirectiona characteristics for the given direction.

For satisfactory reception from a given direction, the two directionalcharacteristics for the direction concerned must have a sufficientintensity. The systems of the prior art have the operating disadvantagethat, when the condition stated above for reception from a givendirection l and at a given wave length is satisfied, the device cannotbe used for a different Wave length at a given adjustment of the phaseShifters, because the single rhomb directional characteristic and thegroup directional characteristic, which have now both been modied, haveas a rule such a different orientation that from no direction issuitable reception possible. The single rhomb directional characteristiccannot be modified by simple means. i

The group directional characteristic, however, can be varied by theintroduction of differences in propagation time of which the valuesincrease equally in the lead-in feeders of the individual rhombs, whichvariation may be attained by means of the phase shifters referred toabove. These phase Shifters in such prior art systems must be adjustedin a different way for each wave length.

These prior art systems employing numerous t phase Shifters are ratherexpensive, and hence the problem arises of providing an antenna systemwhich is suitable. for the reception of different wave lengths Withoutphase shifters or with a smaller number of phase Shifters, or with othermeans to be adjusted for each separate wave length.

In effecting the solution of that problem, it is necessary that thegroup directional characteristie and the individual rhomb directionalcharacteristic shall have for each different wave length substantiallythe same orientation relatively to each other, which orientation invitself will depend, of course, on the Wave length.

One of the features disclosed in the present invention is the provisionof a system wherein two or more rhombic antennae are placed with theirlead-in feeding points in such spaced relation, and are connected to thereceiver by means of transmission lines having such dilerences inpropagation time, that the angle of maximum sensitivity or effectivenessfor each frequency in the aforesaid. vertical plane, Within at least anoctave of frequencies, is equal, or almost equal, for both the groupdirectional'characteristic and the individual rhomb directionalcharacteristic.

With such a system,fthe directional properties or directional eifectcannot be controlled in the way that is possible when phase Shifters areutilized. However, this control of directional eect is possible whenemploying two or more of these systems with the systems interconnectedover phase rotators or phase Shifters. Compared to the relatively smallangle of directivity in transmitting or receiving intensity is ofsatisfactory strength (in which satisfactory strength may be defined,for example, as 50% of the maximum receiving power) are closer than witha device in which all rhombs are coupled over phase rotators.

If it should be necessary to have ,available a wider span or interval ofsteerable directivity, another series of rhombs differently dimensionedcan be utilized for the next interval, and so on.

A"Asthese series'can be arranged in superposed relation over thesame-space of ground, no further space is required to this end.

In Vone preferred embodiment of the invention,

two series of rhombs are used, each series consisting of two groups ofrhombs, there being a phase shifter between the two groups of eachseries. The groups of the first series each have `two rhombs, and thegroups of the second series each have four rhombs. Such a combinationpermits of directive control between two angles, rthe sines of which are1:2.8. This is amply sufficient, since a rhombic array according to theMUSA system is variable between two angles, Vthe vsines of whicharerelated as 1:2.45 withl the above power condition or requirement.

In this preferred embodimentof the present invention, four feedersarrive at the receiver, one from eachgroup of rhombs; These feeders areterminated at the receiver and are connected to the input of a highfrequency amplifier. The outputs of two of these high frequencyramplifiers, one associated 'with' one series of rhombs and the otherassociated with the other series of rhombs, are connected to phaseShifters, which may again be followed byk high frequency ampliers. Theoutputs of these devices are, insoiaras they are associated with groupsof rhombs of the same series, paralleled on the input of a receiverarranged to rectify the signal. The receiver outputs, which'correspondin number to the number of series of rhombs, are paralleled onfthe lowfrequency output byv way of networks for correcting diiferences inpropagation time. Since the various series of rhombs are adjusted todifferent angles, they receive rays which, having been emittedsimultaneously, arrive with different retardations. It may be pointedout here that the Wide band characteristic mentioned at the end of theabove-mentioned article of the Bell System Technical Journal on the MUSAsystem therein described relates exclusively to very narrow bands, ascompared with an octave.

The invention will be exemplified below with reference to theaccompanying drawing illustrating one preferred embodiment of theinvention. In this drawing:

Figure 1 is a diagram representing the received voltage as a function ofthe angle of wave arrival for one rhomb and for combinations of rhombs;and

Figure 2 is a diagram schematically illustrating the antenna system,together with the connections with the receivers, etc.

' Referring rst to Figure 2, this gure illustrates two separate seriesof rhombic antennae,

one series being indicated by the rhombs designated l to 4 inclusive,and the other series being indicated by the rhombs designated 9 to I6inclusive. In the first series, 1 4, the two rhombic antennae l and 2constitute one group, and the other rhombic antennae 3 and 4 constitutea separate group. These two groups are connected in group arrangement byxed feeders 5 and 6 for the lirst group, and by xed feeders 1 and 3 forthe second group, the points of juncture of the respective pairs offeeders being indicatedV at 50 and 5l. Each pair of feeders is connectedto the left hand extremity of its respective rhomb. The right handextremity of each rhomb is shown as being terminated by a terminating,resistance 55 which equals the characteristic antenna resistance.

The other series of eight rhombio antennae 9-l6 is likewise divided intotwo groups, one group consisting of the rhombs, 9, Il), Il and i2, andthe other group consisting of the rhombs I3, I4, l5 and I6. The rstgroup of rhombs 9-I2 in this second series is provided with pairs offeeders l1, I8, i9 and 20, respectively, which have a point of junctureindicated at 25. The second group of rhombs lil-I6 in this second seriesalso has pairs of feeders 2|, 22, 23 and 24 which have a point ofjuncture indicated at 26. The mutual or interspacing distances of therhombs and the lengths of their connecting lines, both between the twogroups of antennae and between the receivers and the junction points 5Iand 26, must satisfy certain requirements in order that the combinationsof rhombs shall have the same directional characteristic as a singlerhomb with regard to dependence of the angle for maximum effectivenessof reception on a given frequency or wave length. In this regard, thedilerence of the distances from juncture point 5l and its companionjuncture point 26 to the receiver, as compared to the distances fromjuncture point 5U and its companion juncture point 25 to the receiver,should be taken into account, and not these distances themselves. Aneffort has been made to indicate this in the drawingfby inclined lines.The above dependance of the angle on frequency is of such nature that,for a given antenna construction, at a certain wave length M, a givenangle of arrival Ao will result in maximum effectiveness of reception.The relation between wave length A and the angle A for which thereception remains a maximum, may be stated for small angles to beapproximately This formula is also valid for a series of rhombs if thedistance of two of these is given by i M 2sin2 Aocos A0 and if thelength of their connecting line equalsing line leads should be omitted.

The series of large rhombs I, 2, 3 and d is built in accordance with theabove description and equations. Similarly, the lengths of the feeders 5and 8 with their connection at junction point 553, and also the lengthsof the feeders 'l and 3 with their connection at junction point E l areproportioned or chosen in accordance with the above conditions. Thedifference in length of the lines from point 5S to the receiver incomparison with the length of the lines from point 5i to the receiver isof such value that, according to the above formula, the immediateparalleling of the lines from points 56 and 5i to the receiver willestablish for the series of rhombs l, 2, 3 and li a dependence in theabove sense which is equal to that of a single rhomb.

The foregoing also applies to the series of eight rhombs 9 9 inclusive,making up the two groups of rhombs s-E and i3-i$, respectively.

The lines coming from the points 51B, 5i, 25 and 26 are led to thereceivers through tubes 2, 28, 29 and 3@ and arrive at inputtransformers 35, 36, Si and 38.

The rhomb dimensions may be calculated according to the methods given inthe article by Bruce appearing in Proceedings oi the Institute of RadioEngineers of January 1935, starting on page 24, and more particularlyaccording to the Alignment Design Method appearing on page 3G.

Referring to the values tb and Z appearing at rhomb i in Figure 2, wehave, according to the above method:

yb and the side Z may be chosen in accordance with the formulae 0.371 2M(1-a2) Sinz A0 If a is chosen smaller than 2, the maximum will, incomparison to Bruces method, remain in this Reduced project, practicallyin the same place. If a=\/2, the rhombs will become so much smaller thatthe adjacent angular points of subsequent rhombs of each series may besuspended on the same mast. Of course, the length may also be calculatedaccording to Bruce, and the system will then consist of rhombs in whichevery succeeding rhomb somewhat overlaps the previous one. From thepoint of View of operation there is no objection to this, but more poleswill be required.

At the receiver shown at the left hand side of Figure 2, thetransformers 35, 3S, 3l and 38 lead to the high frequency ampliers 3|,32, 33 and 36. It will be noted that the ampliers 3l and 33 have phaserotators 39 and @il interposed in their outputs. Beyond these phaserotators, the outputs of the two ampliiers of each series are connectedtogether in parallel relation, as indicated at lil and 42, respectively.Interposed in these parallel connections il and 42 are receivers d3 and"Ll which rectify the signals. In the output circuit of one of thesereceivers is connected a retardation or delaying network-l5 forcorrecting diierences in propagation time. Beyond this retardationnetwork 135, the outputs of the two receivers are paralleled t0 thecommon output 46 leading to a conventional translation device.

The two series of rhombic antennae i-i and S-l 6, respectively, may becontinuously in simultaneous operation.

Cil

It has been found possible with the system des scribed to control anglesof arrival in a sector between 8 and 20 from the horizontal.

The choice of a denite angle within this sector is effected by means ofthe phaserotators 39 and 0, the action of which will be explained inconnection with Figure 1.

This Figure 1 shows some characteristics of rhombic antennae andcombinations of rhombs. On the horizontal axis, the proportion of sinA:sin Am has been kset out, the value of Am giving the angle for whichthe rhomb or combination of rhombs supplies maximum current to thereceiver. The ordinates in this Figure 1 are currents. It should beobserved that actually the diagram should be constructed as a functionof the angle. However, it has been found that the plot; ting of thecharacteristics as a function of the independent variable chosen gives acurve which, with a considerable degree of exactness, is valid for anyvalue of am when this value is less than approximately 30, as will bethe case in practical operation. The maxima of the different curves havebeen taken as equal. Curve a is for a single rhomb, b for two rhombs, cfor four rhombs and d for eight rhombs. If the rhombs are all of equalsize, the maximum of curve d would be eight times as high as that ofcurve a; the scale is thus eight times as small for curve d.

rihe curves given are validfor an adjustment of the phase rotators inwhich the latter do not bring about a phase rotation. Let us now see howthe curve of the 8-fo1d series varies with displacement of the phaserotator 40. From such description, the action of the other phase rotator(is will then be easily understood.

The '-fcid series consists of two groups of four rhombs, according towhich characteristic c should be used. Ii phase rotator it is varied,the currents of the two curves c will no longer be in phase in themaximum, but the currents of both groups are mutually in phase for anangle, which is different from that of the original maximum, it will beclear that the point of maximum reception for the series of 8 rhombswill be displaced. It has been found that this displacement may becontinued until the current value has been reduced to about IAA/2,without undue increase of the secondary maxima or side loops, which arenot shown in the iigure.

in operation, the maximum of each series of rhombs will be so adjustedthat it yields maximum reception, in connection with the direction fromwhich the rays arrive. Therefore, the receiving station shouldpreferably be provided with apparatus permitting of the measurement ofthe signal strength behind each series of rhombs separately.

If receiving conditions are particularly unfavorable, the combination ofreceptions of the two series of rhombs on the output 'it may bedispensed with, i. e., one of the series of rhombs may remain entirelyunused. Transformers 35 and 3'! and the associated transformers 36 and3S may also be paralleled when one of the series of rhombs is put out ofaction, because no strong dependable signals may be received thereon. Itmay be that when using such a circuit connection the introduction ofintermediate amplication becomes desirable. With such circuit, the twophase rota-tors 3s and d will be in connection with a single series, andconsequently two rays or waves from the reception range of that seriesare susceptible of isolation and of being fed to the receivers 43 and44.

l L 2 sin2 A@ cos A0 and leads connecting said spaced rhombs with Vthereceiver having lengths substantially represented by l lo N,

2 sur Aff 2 in which 0=wave length and A0=angle of arrival above ahorizontal plane for which maximum reception is obtained with the givenwave length and antenna construction, whereby with a given frequencychange in a given range of frequencies the directional characteristicfor the group of rhombs is oriented to a new angle of maximumeffectiveness which is substantially equal to the angle of maximumeiiectiveness established for a single rhomb with the same frequencychange.

2. A directional antenna system as claimed in claim l characterized bythe fact that there is a plurality of groups of rhombic antennae inend-to-end array, said groups being arranged in series relation and eachgroup having the interconnections therebetween as set forth in claim 1,each two groups of said series having an individual phase rotator forinterconnecting the output paths of the antennae of its associated twogroups.

3. In a directional antenna system, the combination of a series ofrelatively large rhombic antennae in end-to-end array, a series of re1-atively smaller rhombic antennae in end-to-end array, one of said seriesbeing in superposed 'relation to the other, and translating means havingcommon connection with both series of antennae.

4. In a directional antenna system the combination of a series ofrelatively large rhombic antennae in end-to-end array, a series ofrelatively smaller rhombic antennae in end-to-end array, each seriescomprising a plurality of groups of antennae, one of said series beingin superposed relation to the other, phase shifting means connectedbetween groups in one of said series, and translating means havingcommon connection with both series of antennae.

5. In a directional antenna system the combination of a series ofrelatively large rhombic antennae in end-to-end array, a series ofrelatively smaller rhombic antennae in end-to-end array, each seriescomprising a plurality of groups, each group comprising at least tworhombic antennae, one of said series being in superposed relation to theother so that both series of relatively large antennae and relativelysmaller antennae can be carried by the same supporting poles,independently operable phase Shifters connected between groups in saidtwo series, and translating means jointly controlling or controlled byboth series of antennae.

6. In a multiple unit steerable antenna system.

the combination of a iirst series of rhombic antennae of relativelylarge size, a second series of rhombic antennae of relatively smallersize, each of said series comprising at least two groups, a phaserotator between the groups of said first series, a phase rotator betweenthe groups of said second series, and translation means connected toboth series of antennae.

'7. In a multiple unit steerable antenna system, the combination of afirst series of rhombic antennae of relatively large size, a secondseries of rhombic antennae of relatively smaller size, each of saidseries comprising at least two groups, a phase rotator between thegroups of said irst series, a phase rotator between the groups of saidsecond series, one of said series being in superposed relation to theother, and a common output circuit connected to both series of antennae.

8. In a multiple unit steerable antenna of the class described, thecombination of a first series of rhombic antennae each of relativelylarge size, a second series of rhombic antennae each of relatively smallsize, each of said series comprising a plurality of groups, each groupcomprising at least two antennae, there being at least twice as manyantennae in each group of said second series as there are in each groupof said first series, amplifiers foreach of said groups, phase rotatorsconnected only between groups in each series, and a translation deviceconnected in joint control relation with both series ofv antennae.

9. In a multiple unit steerable antenna of the class described, thecombination of a first series of rhombic antennae each of relativelylarge size, a second series of rhombic antennae each of relatively smallsize, each of said series comprising a plurality of groups, each groupcomprising at least two antennae, there being at least twice as manyantennae in each group of said second series as there are in each groupof said first series, high frequency amplifiers for each oi' saidgroups, phase rotators connected only between groups in each series,said phase rotators being mutually independent, receivers for each ofsaid series, one of said series of rhombic antennae being inpredetermined physical relationship to the other series of rhombicantennae, and a common output circuit `ointly connected with both seriesof antennae.

10. In a multiple unit steerable antenna of the class described, thecombination of a rst series of rhombic antennae each of relatively largesize, a second series of rhombic antennae each of relatively small size,each of said series comprising a plurality of groups, each groupcomprising at least two antennae, there being at least twice as manyantennae in each group of said second series as there are in each groupof said rst series, one of said series being in superposed relation tothe other, high frequency amplifiers for each of said groups, phaserotators connected only between groups in each series, said phaserotators being mutually independent, receivers for each of said series,a retardation network in the output of one of said yreceivers forcorrecting differences in propagation time, and a common output circuiton which the outputs from said receivers are paralleled.

l1. In a multiple unit steerable antenna of the class described, thecombination of a iirst series of rhombic antennae each of relativelylarge size, a second series of rhombic antennae each of relatively smallsize, each of said series comprising a plurality of groups, each groupcomprising at least two antennae, there being at least twice as manyantennae .in each group of said second series as they are in each groupof said rst series, ampliers for each of said groups, phase rotatorsconnected-only between groups 'in each series, said phase rotators beingmutually independent, receivers for each of said series for rectifyingthe signals, and a common output circuit on which the signals rom saidreceivers are paralleled.

12. In a multiple unit steerable antenna or the class described, thecombination of a iirst series of rhombic antennae each of relativelylarge size, a second series of rhombic antennae each of relatively smallsize, each or said series cornprising a plurality of groups, each groupcomprising at least two antennae, there being at least twice as manyantennae in each group of said second series as there are in each groupof said first series, amplifiers for each of said groups, phase rotatorsconnected between groups in each series, receivers for each of saidseries for rectifying the signals, a retardation network in the outputof one of said receivers for correcting diferences in propagation time,and a common output circuit on which the signals from said receivers areparalleled.

13. In a multiple unit steerable antennae system, the combination of aseries or" individual rhombic antennae units arranged in end on array,said series comprising a plurality of groups, each group comprising twoor more of said individual rhombic units, and connecting leads extendingfrom the feeding points of said rhombic units for connection withtranslation apparatus, the distances between feeding points of the unitsbeing substantially equal to:

i t 2 sin2 A0 cos A@ and the lengths of said connecting leads beingsubstantially equal to:

1 )o t ST Acta (in which ko=wavelength and Ao=angle of wave arrivalabove a horizontal plane for which maximum reception is obtained withthe given wave length and antenna construction.)

14. In a multiple unit steerable antenna of the class described, thecombination of a series of individual rhombic antennae arranged inendto-end array and each having a terminating resistance at one end ofeach rhomb and a pair of connecting leads extending from the other end,said series comprisin at least two groups, each group comprising atleast two individual antennae, a separate amplifier for each groupconnected jointly with the connecting leads from the two or moreantennae of that group, the spacing distances between connecting leadends of the two or more antennae in each group being substantially equalto i t 2 sin2 A0 cos A0 and the lengths of the connecting leadsextending therefrom, being substantially equal to a single rhomb, thedirectional"characteristic for the group of rhombs is oriented with a'given frequency change to a new angle of maximum eiectiveness which isequal to the angle or" maximum eectiveness established for a singlerhomb with said given frequency change, detector means receiving theoutput of said amplifiers, phase shifting means operatively interposedbetween one of said amplifiers and said detector means, and an outputcircuit leading from said detector means. l

15. In a multiple unit steerable antenna of the class described, thecombination of a series of individual rhornbic antennae arranged inendto-end array `and each having a pair of connecting leads extendingfrom one end, said series comprising atleast twoA groups, each groupcomprising at least two lindividual antennae, a separate amplifier foreach group connected jointly with the connecting leads from the two ormore antennae of that group, the spacing distances between correspondingpoints of the two or more antennae in each group being substantiallyequal to i t 2 sin2 A0 cos A0 and the lengths of the connecting leadsextending from said latter antennae, being substantially equal to inwhich M=wave length, and A0=the angle of wave arrival above a horizontalplane, for which maximum reception is obtained with the given wavelength, whereby a sharper directional characteristic is attained and theangle of maximum effectiveness in the vertical plane, for a substantialrange of frequencies is substantially the same for said group ofantennae as for the individual antenna, output means receiving theoutput from said amplifiers, and phase shifting means interposed betweenone of said ampliers and said output means.

1S. In an antenna system of the class described, the combination of arst series of relatively large rhombic antennae arranged in an end onarray, a second series of relatively smaller rhombic antennae in an endon array, the difference in size being operative to provide a widerrange of wave lengths over which said system is adjustably responsiveeach of said series comprising a plurality of groups to provide asharper directional characteristic, each of said groups comprising atleast two individual antennae, there being a larger number of individualantennae in each group of said second series than there are in eachgroup of said rst series, leads extending from each individual antenna,and translation means having common connection with both said iirst andsaid second series of antennae through said leads, said antennae beingarranged in a predetermined relative spaced relation and said leadsbeing constructed of different lengths and arranged to eiiect with saidpredetermined antenna spacing, an angle of maximum electiveness in thevertical plane for each frequency, which over a substantial range offrequencies is substantially the same for the group in each series asfor the individual rhomb in that series. i

17. In an antenna system of the class described, the combination of afirst series of relatively large rhombic antennae arranged in an 1l endon array, a second series of relatively smaller rhombic antennae in anend on array, each of said series comprising a plurality of groups, eachof said groups comprising at least two individual antennae, there beinga larger number of individual antennae in each group of said secondseries than there are in each group of said first series, a rst receiverfor said first series, a phase shifter interposed between one of thegroups of said rst series and said rst receiver, a second receiver forsaid second series, a phase shifter interposed between one of the groupsof said second series and said second receiver, a common output circuitfor receiving the output from both of said receivers, and a retardationnetwork interposed between one of said receivers and said common outputcircuit.

HENDRIK C. A. VAN DUUREN.

12 REFERENCES CITED The following references are of record in the fileof this Ipatent:

UNITED STATES PATENTS

